Product category: Power Supply ICs and Controllers
News Release from: National Semiconductor | Subject: LM5116
Edited by the Electronicstalk Editorial Team on 27 February 2007
Buck controller has ultrawide input
range
Current-mode buck controller features a unique combination of high performance, flexibility and ease of use for DC/DC power supply designs.
New from National Semiconductor, the LM5116 is billed as the industry's first 6 to 100V current-mode buck controller for use in telecommunications, automotive and industrial control applications The LM5116 features a unique combination of high performance, flexibility and ease of use for DC/DC power supply designs
This article was originally published on Electronicstalk on 5 Jan 2001 at 8.00am (UK)
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The device joins National's portfolio of synchronous buck controllers, offering extended input voltage range and load current capability.
National is currently demonstrating the LM5116 at the Applied Power Electronics Conference and Expo (APEC) in Anaheim, California (until 1st March 2007).
The LM5116 is well-suited for step-down regulator applications from a high voltage or widely varying input supply.
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The current mode control utilising National's patented emulated current-mode (ECM) technology reduces noise sensitivity of the pulsewidth modulation (PWM) circuit.
It enables reliable control of very small duty cycles necessary in high input voltage applications.
Additional features include thermal shutdown, programmable soft-start, frequency synchronisation, cycle-by-cycle current limit and adjustable line undervoltage lockout (UVLO).
Emulated current-mode control overcomes the noise susceptibility and duty cycle limitations of traditional peak current-mode control by emulating the buck switch current signal, which is used for pulsewidth modulation.
The emulated current signal is developed by charging a capacitor with controlled currents that produce a capacitor voltage waveform directly proportional to the current in the buck switch.
Developing the current signal for the PWM without directly measuring the buck switch current minimises the effect of switching noise, while maintaining the benefits of the current-mode control.
The LM5116 has an ultrawide input range up to 100V, with a programmable output range from 1.215 to 80V.
The reduced noise sensitivity of the PWM control circuit allows reliable operation with very small duty cycles necessary in high input voltage applications.
The emulated current ramp enables the LM5116 to exceed a 20:1 input/output step-down ratio when operating at 500kHz.
The operating frequency is user-programmable up to 1MHz with the capability to synchronise switching to an external clock signal.
A low quiescent-current sleep mode disables the controller and consumes only 10uA of total input current for minimal off-state drain in battery-powered applications.
A user-selectable diode emulation mode enables discontinuous inductor current operation at light load conditions for improved efficiency.
Controlled start up into a pre-biased load is achieved by gradually disabling the diode emulation of the synchronous MOSFET.
The programmable soft-start, input UVLO and voltage tracking features further enhance the system designer's control of the turn-on transition.
The LM5116 is available in a power-enhanced TSSOP-20 package featuring an exposed die attach pad to aid thermal dissipation.
Available now, the LM5116 is priced at US $3.25 in 1000-unit quantities.
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